Connected: An Internet Encyclopedia
RFC 1521 - Appendix H -- Changes from RFC 1341

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### Appendix H -- Changes from RFC 1341

This document is a relatively minor revision of RFC 1341. For the convenience of those familiar with RFC 1341, the technical changes from that document are summarized in this appendix.

1. The definition of "tspecials" has been changed to no longer include ".".

2. The Content-ID field is now mandatory for message/external-body parts.

3. The text/richtext type (including the old Section 7.1.3 and Appendix D) has been moved to a separate document.

4. The rules on header merging for message/partial data have been changed to treat the Encrypted and MIME-Version headers as special cases.

5. The definition of the external-body access-type parameter has been changed so that it can only indicate a single access method (which was all that made sense).

6. There is a new "Subject" parameter for message/external-body, access-type mail-server, to permit MIME-based use of mail servers that rely on Subject field information.

7. The "conversions" parameter for application/octet-stream has been removed.

8. Section 7.4.1 now deprecates the use of the "name" parameter for application/octet-stream, as this will be superseded in the future by a Content-Disposition header.

9. The formal grammar for multipart bodies has been changed so that a CRLF is no longer required before the first boundary line.

10. MIME entities of type "message/partial" and "message/external-body" are now required to use only the "7bit" transfer-encoding. (Specifically, "binary" and "8bit" are not permitted.)

11. The "application/oda" content-type has been removed.

12. A note has been added to the end of section 7.2.3, explaining the semantics of Content-ID in a multipart/alternative MIME entity.

13. The formal syntax for the "MIME-Version" field has been tightened, but in a way that is completely compatible with the only version number defined in RFC 1341.

14. In Section 7.3.1, the definition of message/rfc822 has been relaxed regarding mandatory fields.

All other changes from RFC 1341 were editorial changes and do not affect the technical content of MIME. Considerable formal grammar has been added, but this reflects the prose specification that was already in place.

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Connected: An Internet Encyclopedia
RFC 1521 - Appendix H -- Changes from RFC 1341